Treating lubricating oil fractions



July l1, 1939. c. RV WAGNER TREA'IING LUBRICATING OIL FRACTIONS Filed Dec. 17, 1930 NV AVV NN. NUNRNWU@ ALL W g LUNOOU C023/ l?. Wagner autom/w14 Patented July 11, 1939 UNITED STATES PATENT OFFICE 2,165,949 TREATING LUBRICATING OIL FRACTIONS Cary R. Wagner,

and mesne assignments,

Chicago, Ill., assignor, hy direct of one-half to The Pure This invention relates to an improved process for treating lubricating oil fractions obtained from the distillation of crude petroleum oils for the purpose of removing undesirable Wax cornpounds therefrom, and the process has particular reference to the employment of certain improved solvents which have low solubility for amorphous wax and when admixed with the lubricating oil distillate, permits the latter to be l0 forcedthrough a filter press without necessitating a preheating of the distillate to a cracking temperature to produce a crystalline wax, or what is known as a pressable distillate.

If a cracking operation is resorted to, it destroys or reduces the viscosity of the heavy lubricating fractions at the same time the cracking operation changes the physical properties of the wax from an amorphous to a crystalline form in producing a pressable distillate. Therefore,

such a treating preciable cracking of the lubricating oil stock results in the loss of a most valuable portion of the total potential lubricants in the crude oil from which the initial distillation is effected.

With the present invention, however, by the employment of certainv selected solvents, the crystalline form of the wax is no longer an important factor, and I am enabled to separate, through simple distillation, the lubricating oil fractions from the crude and to then, by the mere addition of my selected `solvents, pass the subsequently chilled lubricating oil fractions directly through a filter press to remove'the undesired wax compounds from the lubricating oil frac- 5 tions at desired temperatures.

AIn accordance with the present invention, a solvent is selected which possesses the unique property of dissolving both oil and Wax in large quantities at temperatures varying around 100 F., but which withdecreasing temperatures shows a rapid decrease in its solvent powers for wax and with only a slight change in its solvent powers for oils. Among certain others, the solvents which I have found to be very effective in carrying out this process are: methyl ethyl ketone, n-butyl alcohol, isobutyl alcohol, isopropyl alcohol, and also mixtures of the solvents in varying proportions with light petroleum naphthas, may be used eifectively in the following described process of dewaxing.

process which involves any ap The following chart shows the relative solvent propertiesof two of the solvents as compared with the regular petroleum naphtha.

Per cent. of wax soluble in solvent 5 Temperature of test M th l N l e y uty ethyl ketone alcohol Naphtha 0.002 0.005 0. 42 10 0. 007 0. 02 l. 40 0. 012 0. 03 2. 40 0. 022 0. 04 3. 90 0. 042 v0. 07 6. 60 0. 084 0. 14 1l. 00

In order to produce a lubricating oil with a pour test of 10 F., it is necessary, in the operation of previous methods, to refrigerate to -l 0 F., or lower, when using naphtha as a solvent in the process of dewaxing. With the use of the above solvents, I have found that it is 20 usually sufficient to cool to the temperature of the desired pour point of the oil or 5 F. lower. Therefore, by my present method, the costs of refrigeration are lower and coincidentally the capacity of the filter presses employed is increased. These factors from an economic standpoint are of considerable importance.

For a further understanding of the invention, reference is to be had to the accompanying drawing, wherein the single figure illustrates diagrammatically apparatus used in carrying out the present invention, and the figure also partakes somewhat of the nature of a flow chart.

The crude oil may be distilled in any conventional manner although, of course, care should be taken that cracking does not occur to any appreciable extent as this will tend to destroy or lower the lubricating value of the distillate. The distillate from about 60 viscosity Saybolt 40 Universal at 100 F. to the end of the distillation is cut into a tank by itself, or if good enough fractionating equipment is present, a distillate of the desired viscosity, flash and fire tests may be produced directly. In the rst case this crude distillate is re-run in a second still taking off distillate until the residue or bottoms in the still have the desired flash, fire and viscosity properties. In most instances, it is satisfactory to produce a distillate of the same viscosity as` the finished neutral oil desired, since removal usually just about oiset each other in their total effect upon viscosity. The process that I shall describe in detail hereinafter Will be one llight fractions from a crude whereina fractionating tower is used to remove distillate containing both wax distillate and what is known as slop wax distillate.

Referring more particularly to the drawing, the crude distillate from the tank A is pumped through a pipe linel into a suitable type of distillation still B, wherein the oil is raised to the desired temperature necessary to effect the vaporization and subsequent separation of the low boilingcompounds present in the distillate or other charging stock. Care should be taken however in the operation of the still B to avoid overheating or cracking of the oils charged thereto. The oils after being heated in the still B pass through an outlet line 2 into any eiiicient form of a fractionating tower, the latter being indicated by the reierence character C. In this fractionating tower there takes place a sharp separation of the low boiling products such as gasoline, kerosene and gas oil, the said low boiling products leaving the top of the tower through the outlet line 3. Line 3 may lead to suitable condensers, not shown, wherein the low boiling products may be fractionally condensed, separated and, collected.

The construction and operation of the tower C is such that the heavier fractions, which comprise the distillate containing the desired neutral lubricating'oil, together with paraiiin wax, petrolatum and other incidental impurities, such as asphaltic bodies, resins, Aand the like, are discharged from the lower portion of the fractionating tower by-way of a pipe line t. Leading into the 'line 4 is a valve controlled pipe line E', which extends from a solvent tank E. This tank may contain any one of the above identied or other equivalent selectedsolvents and the distillate passing through the line 4 is mixed with a suitable quantity of this solvent in proportions depending upon the viscosity and wax content of the oil. Usually these proportions are not less than anequal quantity nor more than iive times the volume of the distillate under treatment. For example, I may say 75% of the special solvent to approximately 25% of the lubricating oil distillate. It will be appreciated however that this example is given merely as one of many and that I am not-limited to the numeral ratio set forth thereby. Y

'I'he distillate is forced through the line t wherein it is mixed with the solvent as above described and is forced through a wax chilling apparatus, indicated at D. 'Ihe distillate-solvent mixture upon entering the wax chillers may possess a temperature of approximately 90 F. This wax chilling apparatus may be of any conventional type such as are commonly used in oil refineries.` It may also be of a tank type with vbrine coolers and agitators instead ofthe closed coll type disclosed in the drawing. After the distillate is cooled in the wax .chillers to the desired pour test, the cooled mixture is then pumped under pressure through a pipe line 5 into a standard filter press, in which the wax is retained upon 4the filter plates F allowing the dewaxed -oil to drop downwardly into the pan or receiver "G, From this receiver, the dewaxed oil is transl* ferred by means of the pipe line G' to a working tank W. t

'I'hedewaxed oil passes from the tank W Owing to the fact that these solvents are miscible with water, it is preferred not to use `a steam distillation in recovering the solvent.

In order to overcome excessively high temperatures in the recovery still, a small amount of neutral gas or refinery residue gas is introduced through a pipe line lil into a perforated coil disposed in the bottom of the still H towards the end of a given distilling operation. This'gas acts substantially like steam in reducing the temperature required to secure complete distillation of the solvent and yet avoids the presence of water in the recovered solvent. Before pumpingA out the still H, however, at the end of a distillation period, it is desirable to pass steam through the oil for a few minutes to purge it of dissolved gas. This steam may enter the still H through the pipe line Il andmay find exit through the line i2.

The dewaxed oil in the still H now has the desired flash, nre and pour characteristics but, on the other hand, may possess a bad color and other impurities. Therefore, to correct this situation, the distillate is withdrawn from the still I-ll by way of a pipe line 9 into a cooler J and thence through aline i3 into an acid treating agitator K. The oil in the agitator K is mixed with concentrated sulphuric vacid at a temperature between '15 to 80 F. After being agitated in the unit K, the oil-acid mixture is passed through a line ld into a settling tank L. The acid sludge formed by the operation in K is withdrawn from tank L through an outlet line l5 and suitably removed from the system. The acid treated oil is withdrawn from the tank L through a line it and enters a caustic agitator M, in which the oil is neutralized with caustic soda and is dischargedv from the agitator M through aline lll and enters a settling tank N. The caustic sludge is withdrawn from the settling tank N and is discharged from the process through a line lli. They neutralized oil is then withdrawn through a pipe line l il and enters the filter O containing fullers earth or its equivalent. The filtered oil leaves the ilter O and passes by way of a line 20 to a suitable storage tank as a finished neutral lubricating oil.

In view of the foregoing, it will be seen that the present invention provides a method of treating lubricating oil fractions of crude oil which particularly avoids any step or operation tending to detract from the ultimate value of the end product as a lubricating oil. Especially, the process overcomes the necessity for overheating or cracking the oil during its initial distillation for the purpose o f producing a solvent containing pressable distillate having a crystalline wax content. While the physical equipment employed by the'present invention is somewhat similar to that'now in general use, yet there are marked dierences which are of considerable importance. For'example, in the operation of the initial distillation still, such as the one indicated at B, thel heated oils do not attain a cracking temperature as has usually been the practice to produce a pressable distillate and second, so far as, I am aware, it is novel to produce a pressable distillate containing the selected solvents above identified. The present invention also enables bricating oil of a certain pour point to operate at a higher temperature than has been customary heretofore and also increases the capacity of the filters F in the matter of producing dewaxedy oils. The particular importance of these operations will be appreciated by those skilled in the art.

In the ordinary processes heretofore employed, it is not possible to filter-press wax distillate unless the wax has been cracked to produce what is known as a crystalline Wax or, as it is sometimes termed, pressable distillate. This cracking operation destroys or minimizes, as above explained, the viscosity of the heavy lubricating fractions at the same time that it produces the crystalline form of the wax and loses a most valuable portion of the total potential lubricants in the crude. With my present method, I am not concerned as to the crystalline form of the Wax, and since no cracking of the oil has taken place in the preparation of the distillate, I have lost none of its most viscous products. The diierence in the yield of lubricants from crude oil may be readily seen when it is noted that in one grade of light Pennsylvania crude, by conventional methods, there was made 6.0% of 150 Viscosity neutral oil, while the present method yielded 9.0 to 10.0% of the same viscosity neutral oil. In heavier oils the differences are still more in favor of the process comprising the present invention.

What is claimed is:

1.- The process of producing ,lubricating oil from an uncracked wax distillate which comprises mixing said uncracked distillatehaving a boiling point above that of gas oil with a solvent liquid containing suiiicient methyl ethyl ketone so that at temperatures of approximately 10D F. the solvent liquid has substantially complete solvent action on said distillate and at a temperature of F. has substantially no solvent action on the wax-containing bodies therein and upon removal of said Wax-containing bodies and sol- Vent the said distillate has a cold pour point substantiallyl the same as the temperature of refrigeration to which thedistillate is subjected for Wax removal, refrigerating the mixture to a temperature substantially similar to the low pour point desired in the final product to form apressable wax mixture, pumping said mixture under .pressure into a lter press, separating the wax from diluted oil, in the absence of extraneous cellular filter aid material, by means of said filter press, and separating the solvent liquid from the separated oil solution.

2. The method of dewaxing uncracked petroleum Wax distillate Within the lubricating oil vrange which comprises completely dissolving said distillate in methyl ethyl ketone, chilling the solution to a temperature suflicient tol solidify the wax present in said distillate and to form a filterrable wax mixture, introducing the filterable Wax CERTIFICATE OF CORRECTION.

Patent No. 42,165,9LL9. July 11, 1959.

CARY R. WAGNER. It is hereby certified that theabove numbered patent was erroneously issued to the inventor, said nCarry R. Wagner" and "The Pure Oil Company" as assignee of one-half interest, whereas said Letters Patent should have been issued to The Pure Oil Company, acorporation of Ohio, said corporation being assignee by direct andmesne assignments of the entire interest in said invention, as shown bythe record of assignments in this office;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the oase in the Patent Office.

Signed and sealed this 21st dayof' November, A. D. 1959.

ellz AI Sdale Ac Comuni-s510116? O1 Pa he] t S 

